Editing Anatomical terms of location

{{Short description|Standard terms for unambiguous description of relative placement of body parts}}
{{Good article}}
{{Anatomical terminology series}}

Standard '''anatomical terms of location''' are used to describe unambiguously the [[anatomy]] of [[human]]s and other [[animal]]s. The terms, typically derived from [[Latin]] or [[Greek language|Greek]] roots, describe something in its [[standard anatomical position]]. This position provides a definition of what is at the front ("anterior"), behind ("posterior") and so on. As part of defining and describing terms, the body is described through the use of [[anatomical plane]]s and [[anatomical axes|axes]].

The meaning of terms that are used can change depending on whether a [[vertebrate]] is a [[biped]] or a [[quadruped]], due to the difference in the [[neuraxis]], or if an [[invertebrate]] is  a [[non-bilaterian]]. A non-bilaterian has no anterior or posterior surface for example but can still have a descriptor used such as [[proximal]] or [[distal]] in relation to a body part that is nearest to, or furthest from its middle.

International organisations have determined vocabularies that are often used as standards for subdisciplines of anatomy. For example, ''[[Terminologia Anatomica]]'', ''Terminologia Neuroanatomica'', and ''[[Terminologia Embryologica]]''  for humans and ''[[Nomina Anatomica Veterinaria]]'' for animals. These allow parties that use anatomical terms, such as [[anatomist]]s, [[veterinarian]]s, and [[medical doctor]]s, to have a standard set of terms to communicate clearly the position of a structure.

==Introduction==
[[File:Human Neuroaxis-en.svg|thumb|Because of differences in the way humans and other animals are structured, different terms are used according to the [[neuraxis]] and whether an animal is a [[vertebrate]] or [[invertebrate]].]]

Standard [[anatomy|anatomical]] terms of location have been developed, usually based on Latin and Greek words, to enable all biological and medical scientists, [[veterinarian]]s, [[Physician|medical doctors]] and [[anatomist]]s to precisely delineate and communicate information about animal bodies and their organs, even though the meaning of some of the terms often is context-sensitive.<ref name="Dyce2010">{{cite book |last1=Dyce |first1=Keith M. |last2=Sack |first2=Wolfgang O. |last3=Wensing |first3=Cornelis Johannes Gerardus |title=Textbook of veterinary anatomy |date=2010 |publisher=Saunders Elsevier |location=St. Louis, Mo |isbn=9781416066071 |pages=2–3 |edition=4th}}</ref><ref name="Gray's">{{cite book |last1=Standring |first1=Susan |title=Gray's anatomy: the anatomical basis of clinical practice |pp=xvi-xvii|date=2016 |publisher=Elsevier |location=Philadelphia, Pa. |isbn=9780702052309 |edition=41.}}</ref> Much of this information has been standardised in internationally agreed vocabularies for humans (''[[Terminologia Anatomica]]'', ''Terminologia Neuroanatomica'', and ''[[Terminologia Embryologica]]''),<ref>{{cite web |title=TE entry page |url=https://ifaa.unifr.ch/Public/EntryPage/PDF/TE%20User%20Guide.pdf |website=IFAA |access-date=27 February 2025}}</ref><ref name="Fipat">{{cite web |title=International Federation of  Associations of Anatomists|url=https://libraries.dal.ca/Fipat.html |website=Dalhousie University |access-date=22 March 2025 |language=en}}</ref> with ''[[Nomina Anatomica Veterinaria]]'' and ''Nomina Embryologica Veterinaria'' used for [[zootomy|animal anatomy]].<ref>{{cite web |title=Documents and publications |url=https://www.wava-amav.org/wava-documents.html |publisher=World Association of Veterinary Anatomists |access-date=24 March 2025}}</ref>

Different terms are used for those [[vertebrate]]s that are [[bipedal]] and those that are [[quadripedal]].<ref name="Dyce2010"/> The reasoning is that the [[neuraxis]], and therefore the [[standard anatomical position]] is different between the two groups.<ref name="Gray's"/> Unique terms are also used to describe [[invertebrate]]s, because of their wider variety of shapes and [[Symmetry in biology|symmetries]].<ref name="Kardong2019">{{cite book |last1=Kardong |first1=Kenneth V. |title=Vertebrates: comparative anatomy, function, evolution |date=2019 |publisher=McGraw-Hill Education |location=New York, NY |isbn=9781260092042 |page=16 |edition=Eighth, international student}}</ref>

===Standard anatomical position===
{{Main|Standard anatomical position}}
[[File:Anatomical position.jpg|thumb|A male and female human in the [[standard anatomical position]]]]

Because [[animal]]s can change orientation with respect to their environment, and because [[appendage]]s like [[limb (anatomy)|limbs]] and [[tentacle]]s can change position with respect to the main body, terms to describe position need to refer to an animal when it is in its [[standard anatomical position]], even when its appendages are in another position. This helps to avoid confusion in terminology when referring to the same animal in different postures.<ref name="libre3">{{cite web |title=1.4A: Anatomical Position |url=https://med.libretexts.org/Bookshelves/Anatomy_and_Physiology/Anatomy_and_Physiology_(Boundless)/1%3A_Introduction_to_Anatomy_and_Physiology/1.4%3A_Mapping_the_Body/1.4A%3A_Anatomical_Position |website=Medicine LibreTexts |access-date=4 March 2025 |language=en |date=18 July 2018}}</ref> In humans, this refers to the body in a standing position with arms at the side and palms facing forward.<ref name="Gray2016">{{cite web |title=Introduction |url=https://www.bartleby.com/lit-hub/anatomy-of-the-human-body/introduction-53/ |website=Collection at Bartleby.com |access-date=1 March 2025 |date=20 October 2022}}</ref><ref name="libre3"/> In [[quadrupeds]] this is an animal standing upright with all four feet on the ground and the head facing forward.<ref>{{cite book |last=Kumar |first=M.S.A. |date= 2015 |title=Clinically oriented anatomy of the dog & cat |url=https://www.google.com.gt/books/edition/Clinically_Oriented_Anatomy_of_the_Dog_a/ZBSSDwAAQBAJ?gbpv=1&pg=PA9 |publisher=Linus Learning |page=9 |isbn=9781607975526 |access-date=2025-05-08}}</ref> For a [[fish]] this is belly down with neutral appendages. <ref>{{cite book |last=Earls|first=James |date=2023 |title=Functional Anatomy of Movement: An Illustrated Guide to Joint Movement, Soft Tissue Control, and Myofascial Anatomy-- For Yoga Teachers, Pilates Instructors & Movement & Manual Therapists |url=https://www.google.com.gt/books/edition/Functional_Anatomy_of_Movement/dzJ1EAAAQBAJ?gbpv=1&pg=PA15 |publisher=North Atlantic Books |page=15 |isbn= 9781623178420 |access-date=2025-05-08}}</ref>

===Planes===
{{Main|Anatomical plane}}
[[File:Human and goat anatomical planes.jpg|thumb|The standard anatomical planes of both a human and a goat displaying three anatomical planes:
{{legend|#c7dbdc|the midsagittal plane}}
{{legend|#ffc8c3|the transverse plane}}
{{legend|#ffebc1|the dorsal plane, often called the coronal or frontal plane in human anatomy}}]]

Anatomical terms describe structures with relation to four main [[anatomical plane]]s.<ref name="Gray2016"/> Anatomical planes are useful in a number of fields including [[medical imaging]], [[embryology]], and the study of movement.<ref name="libre2025">{{cite web |title=1.4D: Body Planes and Sections |url=https://med.libretexts.org/Bookshelves/Anatomy_and_Physiology/Anatomy_and_Physiology_(Boundless)/1:_Introduction_to_Anatomy_and_Physiology/1.4:_Mapping_the_Body/1.4D:_Body_Planes_and_Sections |website=Medicine LibreTexts |access-date=2 March 2025 |language=en |date=18 July 2018}}</ref>

The four main planes are:

*The '''[[median plane]]''', also called the '''midsagittal plane''', divides the body into left and right parts starting from the [[sagittal suture]].<ref name="Gray2016"/> The median plane passes through the head, [[spinal cord]], [[navel]] and, in many animals, the tail.<ref name="Hyman">{{cite book |last1=Hyman |first1=Libbie Henrietta |title=Hyman's comparative vertebrate anatomy |date=1979 |publisher=Univ. of Chicago Pr |location=Chicago |isbn=9780226870113 |pages=1–6 |edition=3rd}}</ref> 
*The '''[[sagittal plane]]s''', also called the '''parasagittal planes''' or '''paramedian planes''', are planes that are parallel to the median plane.<ref name="Dyce2010"/><ref name="Moore1" />
* The '''dorsal plane''' divides the body into dorsal (towards the backbone) and ventral (towards the belly) parts.<ref>{{cite book |date=2017|title=Nomina Anatomica Veterinaria |url=https://wava-amav.org/downloads/nav_6_2017.zip |publisher=World Association of Veterinary Anatomists |edition=6|page=9 |access-date=2025-05-08}}</ref> In human anatomy '''[[coronal plane]]''' is preferred, or sometimes the '''frontal plane''', and the description may reference splitting the body into front and back parts<ref name="Gray2016"/>, but this phrasing is not as clear for animals with a horizontal spine like [[quadrupeds]] or [[fish]].
* The '''[[transverse plane]]''', also called the '''axial plane''' or '''horizontal plane''', is perpendicular to the other two planes.<ref name="Gray2016"/> In an animal with a vertical craniocaudal axis, like a human, this plane is parallel to the ground; in an animal with a horizontal craniocaudal axis, like a quadruped, the coronal plane divides the animal into anterior and posterior sections.<ref name="Kardong2019"/>

Sagittal planes and transverse planes are used as [[anatomical lines]] to delineate [[Anatomical terminology#Regions|bodily regions]]. There are several transverse planes with clinical relevance in the division of the torso into sections. They include the [[transpyloric plane]], the [[subcostal plane]],  and the [[transumbilical plane]].<ref name="medscape2025">{{cite web |title=Regions and Planes of the Abdomen: Overview, Abdominal Skin, Superficial Fascia |url=https://emedicine.medscape.com/article/1923166-overview?form=fpf |access-date=10 March 2025 |date=19 February 2025}}</ref>

===Axes===
<!--Multiple links redirect to this section-->
[[File:Anatomical axes.svg|thumb|Anatomical axes in a human, similar for other [[Orthograde posture|orthograde bipedal]] vertebrates]]

The three [[Anatomical terminology#Axes|axes]] of a vertebrate, are formed in [[embryonic development]]  before and during the [[gastrulation]] stage.<ref name="Abas2022">{{cite journal |vauthors=Abas R, Masrudin SS, Harun AM, Omar NS |title=Gastrulation and Body Axes Formation: A Molecular Concept and Its Clinical Correlates |journal=Malays J Med Sci |volume=29 |issue=6 |pages=6–14 |date=December 2022 |pmid=36818899 |pmc=9910376 |doi=10.21315/mjms2022.29.6.2 |url=}}</ref> Distinct ends of the embryo are chosen, and the axis is named according to those directions. The three main axes of a [[bilateral symmetry|bilaterally symmetrical]] animal that intersect at right angles, are the left-right, the craniocaudal, and the anteroposterior axes.<ref name="Abas2022"/><ref name="Kardong2019"/> 
* The left-right axis, also known as the horizontal or frontal axis<ref name="Abas2022"/>
* The craniocaudal axis, also known as the rostrocaudal, longitudinal or cephalocaudal<ref name="Abas2022"/>
* The anteroposterior axis, also known as the dorsoventral, or sagittal axis<ref name="UNSW2025">{{cite web |title=Developmental Mechanism - Axes Formation - Embryology |url=https://embryology.med.unsw.edu.au/embryology/index.php/Developmental_Mechanism_-_Axes_Formation#Left-Right_Axis |website=embryology.med.unsw.edu.au |access-date=1 March 2025}}</ref><ref name="amigo2">{{cite web |title=AmiGO 2: Term Details for "dorsal/ventral axis specification" (GO:0009950) |url=https://amigo.geneontology.org/amigo/term/GO:0009950 |website=amigo.geneontology.org |access-date=1 March 2025}}</ref>

An organism that is round, or [[asymmetrical]] may have different axes.<ref name="Kardong2019"/>

==Main terms==
{{Anchor|superior|inferior}}
{{See also|Anatomical terminology#Standard terms}}

===Superior and inferior===
In the [[standard anatomical position|standard human anatomical position]], '''superior''' ({{ety|la|super|above}}) or '''cranial''', describes something that is nearer to the head, and '''inferior''' ({{ety|la|inferus|below}}) or '''caudal''' describes what is below, and nearer to the feet.<ref name="libre3"/> Examples are the [[superior mediastinum]], and [[inferior mediastinum]]. Neuroanatomy examples are the [[superior colliculus]], and the [[inferior colliculus]].<ref name="Moore1">{{cite book |last1=Moore |first1=Keith L. |last2=Dalley |first2=Arthur F. |last3=Agur |first3=Anne M. R. |title=Clinically oriented anatomy |date=2018 |publisher=Wolters Kluwer |location=Philadelphia Baltimore New York London Buenos Aires Hong Kong Sydney Tokyo |isbn=9781496347213 |pages=5–8 |edition=Eighth}}</ref> In veterinary anatomy, the terms superior and inferior are not used except to describe the eye, eyelids, lips and inner ear, using instead '''dorsal''' and '''ventral'''.<ref name="Dyce2010"/>

===Anterior and posterior===
{{Redirect|Anterior}}<!-- [[Posterior]] is a dab page, not redirect -->

'''Anterior''' ({{ety|la|ante|before}}) describes what is in front, and '''posterior''' ({{ety|la|post|after}}) describes what is to the back of something.<ref name="Purves1">{{cite web |last1=Purves |first1=Dale |last2=Augustine |first2=George J. |last3=Fitzpatrick |first3=David |last4=Katz |first4=Lawrence C. |last5=LaMantia |first5=Anthony-Samuel |last6=McNamara |first6=James O. |last7=Williams |first7=S. Mark |title=Some Anatomical Terminology |url=https://www.ncbi.nlm.nih.gov/books/NBK10971/ |website=Neuroscience. 2nd edition |publisher=Sinauer Associates |access-date=7 March 2025 |language=en |date=2001}}</ref> For example, for many [[fish]] the [[gill]] openings are posterior to the eyes and anterior to the tail.

===Dorsal and ventral===
These two terms, used in [[Veterinary medicine|veterinary anatomy]], are also used in [[human anatomy]] mostly in  [[neuroanatomy]], and [[embryology]], to describe something at the back (dorsal, posterior) or front (ventral, anterior) of an organ, or organism.<ref name="Gray2016"/><ref name="Purves1"/>

The '''dorsal''' ({{ety|la|dorsum|back}}) surface, (also '''dorsum''') of an organism or [[organ (biology)|organ]], refers to the back, or upper side, such as in the human, the dorsum of the [[tongue]], the [[dorsum of hand|dorsum of the hand]], and the [[dorsum of foot|dorsum of the foot]].  If talking about the skull, the dorsal side is the top.<ref name="amigo2"/><ref name="Moore1"/>

{{anchor|inserted2020-09-25specificallyfor ventral}}
The '''ventral''' ({{ety|la|venter|belly}}) surface refers to the front, or lower side, of an organism, or organ such as the undersurface of the tongue.<ref name="amigo2"/>

In a [[fish]], the [[dorsal fin]] is on the upper surface and its [[ventral fin]]s (pelvic fins) are on the belly or undersurface.<ref name="SCDNR">{{cite web |title=SCDNR - Fishing Information |url=https://www.dnr.sc.gov/fish/anatomy.html |website=www.dnr.sc.gov |access-date=27 February 2025}}</ref>

The terms are used in other contexts, for example in [[gun turret#Aircraft layout|dorsal and ventral gun turrets]] on a bomber aircraft.

{{Anchor|medial|median|lateral}}

===Medial and lateral<span class="anchor" id="unilateral"></span><span class="anchor" id="bilateral"></span><span class="anchor" id="temporal"></span>===
These terms describe how close something is to the median plane.<ref name="Gray's"/><ref name="Purves1"/> '''Lateral''' ({{ety|la|lateralis|to the side}}) describes something to the sides of an animal, as in "left lateral" and "right lateral". '''Medial''' ({{ety|la|medius|middle}}) describes structures close to the median plane, or closer to the median plane than another structure.<ref name="Purves1"/> For example, in a human, the arms are lateral to the [[torso]]. The [[Sex organ|genitals]] are medial to the legs. '''Temporal''' has a similar meaning to lateral but is restricted to the head.

The terms "left" and "right", or [[sinistral and dextral]], refer to the halves of a bilaterally symmetrical body divided by the median plane.

Terms derived from lateral include:

* '''Contralateral''' ({{ety|la|contra|against}}): on the side opposite to another structure. For example, the right arm and leg are controlled by the left, [[Contralateral brain|contralateral, side of the brain]].
* '''Ipsilateral''' ({{ety|la|ipse|same}}): on the same side as another structure. For example, the left arm is ipsilateral to the left leg.<ref name="Moore1"/>
* '''Bilateral''' ({{ety|la|bis|twice}}): on both sides of the body.<ref name="Moore1"/> For example, bilateral [[orchiectomy]] means removal of [[testes]] on both sides of the body.
* '''Unilateral''' ({{ety|la|unus|one}}) one-sided or single-sided: on one side of the body.<ref name="Moore1"/> For example, unilateral deafness is hearing impairment in one ear.<ref name="Dodson">{{cite journal |last1=Dodson |first1=Kelley M |last2=Georgolios |first2=Alexandros |last3=Barr |first3=Noelle |title=Etiology of unilateral hearing loss in a national hereditary deafness repository |journal=American Journal of Otolaryngology |date=2012 |volume=33 |issue=5 |pages=590-594 |doi=10.1016/j.amjoto.2012.03.005 |access-date=24 March 2025| url=https://www.sciencedirect.com/science/article/pii/S0196070912000658|doi-access=free }}</ref>

'''[[Varus deformity|Varus]]''' ({{ety|la||bow-legged}}) and '''[[valgus deformity|valgus]]''' ({{ety|la||knock-kneed}} ) are terms used to describe angulation or bowing  of a bone or joint within the coronal plane, where the distal portion deviates towards (varus) or away from (valgus) the midline.<ref>{{cite web |last1=Hacking |first1=Craig |title=Valgus vs varus |url=https://radiopaedia.org/articles/valgus-vs-varus-1?lang=us |website=Radiopedia |access-date=24 March 2025}}</ref>

{{Anchor|proximal|distal}}

===Proximal and distal===
{{Redirect2|Proximal|distal|the linguistic terms|Demonstrative#Distal and proximal demonstratives|the dental terms|Glossary of dentistry}}
[[File:Blausen 0019 AnatomicalDirectionalReferences.png|thumb|upright=1.3|Anatomical directional reference]]
{{wiktionary | proximal | distal}}

The terms '''proximal''' ({{ety|la|proximus|nearest}}) and '''distal''' ({{ety|la|distare|to stand away from}}) are used to describe parts of a feature that are close to or distant from the main mass of the body, respectively.<ref name="Seer2025">{{cite web |title=Anatomical Terminology {{!}} SEER Training |url=https://training.seer.cancer.gov/anatomy/body/terminology.html |website=training.seer.cancer.gov |access-date=10 March 2025}}</ref> Thus the upper arm in humans is proximal and the hand is distal. The main mass is taken as the center, the [[chest]], or the [[heart]].<ref name="meaning"/>

"Proximal and distal" are frequently used when describing [[appendage]]s, such as [[fins]], [[tentacle]]s, and [[Limb (anatomy)|limbs]]. Although the direction indicated by "proximal" and "distal" is always respectively towards or away from the point of attachment, a given structure can be either proximal or distal in relation to another point of reference. Thus the elbow is distal to a wound on the upper arm, but proximal to a wound on the lower arm.<ref name="meaning">{{cite web |title=What do distal and proximal mean? |website=The Survival Doctor |url= http://www.thesurvivaldoctor.com/2011/10/04/what-do-distal-and-proximal-mean/ |access-date= 2016-01-07|date=2011-10-05 }}</ref>

This terminology is also employed in molecular biology and therefore by extension is also used in chemistry, specifically referring to the atomic loci of molecules from the overall [[Moiety (chemistry)|moiety]] of a given compound.<ref>{{cite journal|last1= Singh|first1= S |title=Chemistry, design, and structure-activity relationship of cocaine antagonists |journal=Chemical Reviews|date=8 March 2000|volume=100|issue=3|pages=925–1024|pmid= 11749256 |doi= 10.1021/cr9700538}}
</ref>

{{Anchor|caudal|cranial|rostral}}

===Rostral, cranial, and caudal===
[[File:Rostralcaudal.svg|thumb|right|In the [[human skull]], the terms ''rostral'' and ''caudal'' are adapted to the curved [[neuraxis]] of [[Hominidae]], ''rostrocaudal'' meaning the region on C shape connecting rostral and caudal regions.]]

Specific terms exist to describe how close or far something is to the head or tail of an animal. To describe how close to the head of an animal something is, three distinct terms are used:

* '''Rostral''' ({{ety|la|rostrum|beak, nose}}) describes something situated toward the oral or nasal region, or in the case of the brain, toward the tip of the frontal lobe.<ref name="Moore1"/><ref name="Purves1"/>
* '''Cranial''' ({{ety|el|κρανίον|skull}}) or '''cephalic''' ({{ety|el|κεφαλή|head}}) describes how close something is to the head of an organism.<ref name="Moore1"/>
* '''Caudal''' ({{ety|la|cauda|tail}}) describes how close something is to the trailing end of an organism.<ref name="Purves1"/>

These terms are generally preferred in veterinary medicine and not used as often in human medicine.<ref name="Hickman et al. 2003">Hickman, C. P. Jr., Roberts, L. S. and Larson, A. ''Animal Diversity''. McGraw-Hill 2003 {{ISBN|0-07-234903-4}}</ref><ref name="Miller 2002">Miller, S. A. ''General Zoology Laboratory Manual'' McGraw-Hill, {{ISBN|0-07-252837-0}} and {{ISBN|0-07-243559-3}}</ref> For example, in [[horse]]s, the eyes are caudal to the nose and rostral to the back of the head.<ref name="Dyce2010"/>

In humans, "cranial" and "cephalic" are used to refer to the skull, with "cranial" being used more commonly. The term "rostral" is rarely used in human [[gross anatomy]] and refers more to the front of the face than the superior aspect of the organism. But it is used in [[Embryonic development|embryology]], and [[Anatomical terms of neuroanatomy|neuroanatomy]].  Similarly, the term "caudal" is used more in embryology and neuroanatomy, and only occasionally in human gross anatomy.<ref name="Gray's"/> The "rostrocaudal axis" refers to the curved line of the  [[neuraxis]] from the forehead (rostral) towards the tail end (caudal).

===Central and peripheral===
Central and peripheral refer to the distance towards and away from the centre of something. That might be an organ, a region in the body, or an anatomical structure. For example, the [[central nervous system]] and the [[peripheral nervous system]]s.

'''Central''' ({{ety|la|centralis}}) describes something at, or close to the centre.<ref>{{cite web |title=Definition of Central |url=https://www.merriam-webster.com/dictionary/central |website=www.merriam-webster.com |access-date=23 March 2025 |language=en |date=23 March 2025}}</ref>  For example, the [[great vessels]] run centrally through the body; many smaller vessels branch from these. 

'''Peripheral''' ({{ety|la|peripheria}}, originally from [[Ancient Greek]]) describes something that is situated nearer to the body's surface, such as a [[peripheral nerve]].<ref>{{cite web |title=Peripheral |url=https://www.collinsdictionary.com/dictionary/english/peripheral |access-date=23 March 2025}}</ref>

{{Anchor|superficial|deep}}

===Superficial and deep===
These terms refer to the distance of a structure from the surface.<ref name="Gray's"/><ref name="libre4">{{cite web |title=1.4B: Directional Terms |url=https://med.libretexts.org/Bookshelves/Anatomy_and_Physiology/Anatomy_and_Physiology_(Boundless)/1%3A_Introduction_to_Anatomy_and_Physiology/1.4%3A_Mapping_the_Body/1.4B%3A_Directional_Terms |website=Medicine LibreTexts |access-date=4 March 2025 |language=en |date=18 July 2018}}</ref>

'''Deep''' ({{ety|ang}}) describes something further away from the surface of the organism.<ref name="libre4"/> For example, the [[external oblique muscle]] of the abdomen is deep to the skin. "Deep" is one of the few anatomical terms of location derived from [[Old English]] rather than Latin – the anglicised Latin term would have been "profound" ({{ety|la|profundus|due to depth}}).<ref name="Dyce2010"/>

'''Superficial''' ({{ety|la|superficies|surface}}) describes something near the outer surface of the organism.<ref name="Dyce2010"/> For example, in [[skin]], the [[epidermis]] is superficial to the [[subcutis]].<ref name="libre4"/>

=== Combined terms ===
[[File:Posterior Parietal Lobe.jpg|thumb|[[Dorsolateral prefrontal cortex]] highlighted in dark green]]
Many anatomical terms can be combined, either to indicate a position in two axes simultaneously or to indicate the direction of a movement relative to the body. For example, '''anterolateral''' indicates a position that is both anterior and lateral to the body axis (such as the bulk of the [[pectoralis major]] muscle), or to a named organ such as the [[anterolateral tibial tubercle]].<ref name="Moore2018">{{cite book |last1=Moore |first1=Keith L. |last2=Dalley |first2=Arthur F. |last3=Agur |first3=Anne M. R. |title=Clinically oriented anatomy |date=2018 |publisher=Wolters Kluwer |location=Philadelphia Baltimore New York London Buenos Aires Hong Kong Sydney Tokyo |isbn=9781496347213 |page=679 |edition=Eighth}}</ref> The term can also describe the direction and location of something that enters or courses through the body such as the [[anterolateral system]] in the [[spinal cord]], and the [[anterolateral central arteries]].<ref>{{Cite web |title=Anatonomina |url=http://terminologia-anatomica.org/en/Terms/Occurence/4050 |access-date=2025-02-28 |website=terminologia-anatomica.org}}</ref>  Another term '''anteromedial''' is used for example in the [[anteromedial central arteries]].<ref>{{Cite web |title=Anatonomina |url=http://terminologia-anatomica.org/en/Terms/Occurence/4024 |access-date=2025-02-28 |website=terminologia-anatomica.org}}</ref>

In the more internal [[brain]] and [[spinal cord]] of the [[central nervous system]] the terms [[#Dorsal and ventral|dorsal and ventral]] and their combinations are often used in place of anterior and posterior. In these organs numerous references need to be used, and in the brain for example the [[prefrontal cortex]] has the divisions of the [[dorsomedial prefrontal cortex]], and the [[dorsolateral prefrontal cortex]].  And the dorsomedial region has subcompartments that make use of other terms such as the [[anterior cingulate cortex]], and [[infralimbic cortex]]. Structures such as the anterior cingulate cortex may be divided anatomically based on cognitive ([[Dorsum (biology)|dorsal]]), and emotional ([[ventral]]) components.<ref name="Bush00">{{cite journal | vauthors = Bush G, Luu P, Posner MI | title = Cognitive and emotional influences in anterior cingulate cortex | journal = Trends in Cognitive Sciences | volume = 4 | issue = 6 | pages = 215–222 | date = June 2000 | pmid = 10827444 | doi = 10.1016/S1364-6613(00)01483-2 | s2cid = 16451230 }}</ref>

'''Proximodistal''' is the axis of an [[appendage]] such as an arm or a leg, taken from its tip at the distal part to where it joins the body at the proximal part.<ref name="UNSW2025"/>

In [[radiology]], various [[Projectional radiography|X-ray views]] uses [[Projectional radiography terminology|terminology]]  based on where the X-ray beam enters and leaves the body, including the front to back view ('''anteroposterior'''), the back to front view ('''posteroanterior'''), and the side view ('''lateral''').<ref>{{cite book |last1=Hofer |first1=Matthias |title=The Chest X-ray: A Systematic Teaching Atlas |year=2006 |publisher=Thieme |isbn=978-3-13-144211-6 |page=24 |url=https://books.google.com/books?id=iERHEAWOk3oC&pg=PA24 |language=en}}</ref> Combined terms were once generally hyphenated, but typically the hyphen is omitted.<ref>{{cite dictionary |url=http://www.merriam-webster.com/dictionary/dorsolateral |title=dorsolateral |date=29 September 2023 |dictionary=Merriam-Webster}}</ref>

===Modifiers===
[[File:Radiate Oral-aboral Axes.JPG|thumb|Terms can be modified with prefixes and suffixes. In this image showing the [[jellyfish]] species ''[[Chrysaora]]'', the prefix 'ab-', is used to indicate something that is 'away from' the mouth, for example the '''aboral'''. Other terms are combined to indicate axes, such as proximodistal axis.]]

Several terms are commonly seen and used as [[prefix]]es:<ref name="Terms2025">{{cite web |title=medical terms |url=https://www.ucl.ac.uk/lapt/medterms.htm |website=www.ucl.ac.uk |access-date=9 March 2025}}</ref>

* '''Sub-''' ({{ety|la|sub|preposition beneath, close to, nearly etc}}) is used to indicate something that is beneath, or something that is subordinate to or lesser than.<ref name="Terms2025"/> For example, [[Subcutaneous tissue|subcutaneous]] means beneath the skin.
* '''Hypo-''' ({{ety|grc|ὑπό|under}}) is used to indicate something that is beneath.<ref name="Terms2025"/> For example, the [[hypoglossal nerve]] supplies the muscles beneath the tongue.
* '''Infra-''' ({{ety|la|infra|under}}) is used to indicate something that is within or below. For example, the [[infraorbital nerve]] runs within the [[orbit (anatomy)|orbit]].
* '''Inter-''' ({{ety|la|inter|between}}) is used to indicate something that is between.<ref name="Terms2025"/> For example, the [[intercostal muscle]]s run between the [[rib]]s.
* '''Super-'' or ''Supra-''' ({{ety|la|super, supra|above, on top of}}) is used to indicate something that is above something else.<ref name="Terms2025"/> For example, the [[supraorbital ridge]]s are above the [[eye]]s.
* '''Ab-''' ({{ety|la|ab|away}}), and '''ad-''' ({{ety|la|ad|towards}}) are used to indicate that something is towards (ad-) or away from (ab-) something else.<ref name="Terms2025"/> For example [[abduction and adduction]] refer to muscular movement away from, and towards the midline of the body, respectively.

Other terms are used as [[suffix]]es, added to the end of words:
* '''-al''' ({{ety|la|al|pertaining to, of the}}) For example [[femoral neck]].
* '''-ad''' ({{ety|la|ad|towards}}), equivalent to '-ally', is a suffix createing the adverb form to indicate that something moves towards (-ad) something else.<ref name= "GGHDHD">{{cite book |last1=Gordh |first1=Gordon |last2=Headrick |first2=David H |title=A Dictionary of Entomology |publisher=CABI |year=2011 |edition=2nd |isbn=978-1845935429|url=https://archive.org/details/dictionaryofento0000gord}}</ref> For example, "distad" means "in the distal direction,"<ref name="MW2025c">{{cite web |title=Medical Definition of Distad |url=https://www.merriam-webster.com/medical/distad |website=www.merriam-webster.com |access-date=15 March 2025 |language=en}}</ref> as in "arterial blood flows distad/distally." Further examples may include cephalad (towards the cephalic end), orad, craniad, and proximad. The terms "proximally" and "distally" are in more common use in human and veterinary anatomic textbooks, while "proximad" and "distad," are used commonly in insect anatomy.<ref name="Gray's"/><ref name="Dyce2010"/><ref name= "GGHDHD"/>

==Other terms and special cases==
===Anatomical landmarks===
{{See also|List of anatomical lines}}
The location of anatomical structures can also be described in relation to different [[anatomical landmarks]] used in anatomy, [[surface anatomy]], surgery, and radiology.<ref name="Butler">{{Cite book|last1=Butler|first1=Paul|url=https://books.google.com/books?id=YaYSbU6DR9oC&q=surface+anatomy+and+anatomical+landmarks&pg=PA1|title=Applied Radiological Anatomy|last2=Mitchell|first2=Adam W. M.|last3=Ellis|first3=Harold|date=1999-10-14|publisher=Cambridge University Press|isbn=978-0-521-48110-6|pages=1|language=en}}</ref>

Structures may be described as being at the level of a specific [[vertebra]], depending on the section of the [[vertebral column]] the structure is at.<ref name="Butler" /> The position is often abbreviated. For example, structures at the level of the fourth [[cervical vertebra]] may be abbreviated as "C4", at the level of the fourth [[thoracic vertebra]] "T4", and at the level of the third [[lumbar vertebra]] "L3". Because the [[sacrum]] and coccyx are fused, they are not often used to provide the location.

References may also take origin from surface anatomy, made to landmarks that are on the skin or visible underneath.<ref name="Butler" /> For example, structures may be described relative to the [[anterior superior iliac spine]], the [[medial malleolus]] or the [[Medial epicondyle of the humerus|medial epicondyle]].

[[Anatomical lines]] are theoretical lines, using either horizontal transverse planes, or vertical sagittal  planes, used to describe anatomical location. For examples, the mid-clavicular line is used as part of the [[cardiac examination]] to feel the [[apex beat]] of the [[heart]], and the [[axillary lines]] are reference lines for the [[axilla|underarm]] region. Other types of lines in anatomy include the curved [[nuchal lines]] on the [[occipital bone]], and the [[gluteal lines]] on the [[ilium (bone)|ilium]].

===Mouth and teeth===
{{Main|Dental terminology}}

Special terms are used to describe the mouth and teeth.<ref name="Gray's"/> Fields such as [[osteology]], [[paleontology]] and [[dentistry]] apply special terms of location to describe the mouth and teeth. This is because although teeth may be aligned with their main axes within the jaw, some different relationships require special terminology as well; for example, teeth also can be rotated, and in such contexts terms like "anterior" or "lateral" become ambiguous.<ref name="Folkens2000">{{cite book|author=Pieter A. Folkens|title=Human Osteology|url=https://books.google.com/books?id=lrLL-X5bg_0C&pg=PA558|year=2000|publisher=Gulf Professional Publishing|isbn=978-0-12-746612-5|pages=558–}}</ref><ref name=SmithDodson2003>{{cite journal |last1=Smith |first1=J. B. |last2=Dodson |first2=P. |year=2003 |title=A proposal for a standard terminology of anatomical notation and orientation in fossil vertebrate dentitions |journal=Journal of Vertebrate Paleontology |volume=23 |issue=1 |pages=1–12 |doi=10.1671/0272-4634(2003)23[1:APFAST]2.0.CO;2 |s2cid=8134718 |url=https://repository.upenn.edu/ees_papers/34 }}</ref> For example, the terms "distal" and "proximal" (or "mesial") are used for surfaces of individual teeth relative to the midpoint of the [[dental arch]], and "medial" and "lateral" are used in the standard sense relative to the median plane.<ref name=Rajkumar2017>{{cite book |last1=Rajkumar |first1=K. |last2=Ramya |first2=R. |title=Textbook of Oral Anatomy, Physiology, Histology and Tooth Morphology |publisher=Wolters kluwer india Pvt Ltd |isbn=978-93-86691-16-3 |pages=6–7 |url=https://books.google.com/books?id=YvbsDwAAQBAJ&dq=distal+and+%22proximal+mandibular+symphysis+dental+anatomy&pg=RA1-PA7 |language=en|year=2017}}</ref> Terms used to describe structures include "buccal" ({{ety|la|bucca|cheek}}) and "palatal" ({{ety|la|palatum|palate}}) referring to structures close to the [[cheek]] and [[hard palate]] respectively.<ref name=Rajkumar2017 />

===Hands and feet===
{{Redirect|Plantar|the fictional frog family|List of Amphibia characters{{!}}List of ''Amphibia'' characters}}
[[Image:Hand Directional Axes.JPG|thumb|right|Anatomical terms used to describe a human hand]]

Several anatomical terms are particular to the hands and feet.<ref name="Gray's"/> Additional terms may be used to avoid confusion when describing the surfaces of the hand and what is the "anterior" or "posterior" surface. The term "anterior", while anatomically correct, can be confusing when describing the [[Hand|palm]] of the hand; Similarly is "posterior", used to describe the back of the hand and arm. This confusion can arise because the forearm can [[pronate]] and [[supinate]] and flip the location of the hand. For improved clarity, the directional term '''palmar''' ({{ety|la|palma|palm of the hand}}) is commonly used to describe the front of the hand, and '''dorsal''' is the back of the hand. The [[palmar fascia]] is ''palmar'' to the [[tendon]]s of muscles which flex the fingers, and the [[dorsal venous arch]] is so named because it is on the dorsal side of the foot.

In humans, '''volar''' can also be used synonymously with ''palmar'' to refer to the [[Hand#Areas|palm of the hand]], and can also be used to refer to the [[Sole (foot)|sole of the foot]].<ref name="Collins3">{{cite web |title=Volar |url=https://www.collinsdictionary.com/dictionary/english/volar#google_vignette |access-date=16 March 2025}}</ref> But ''palmar'' is used exclusively for the palm of the hand, and '''plantar''' is used exclusively for the sole of the foot.<ref name="Collins3"/><ref>{{cite web |title=Definition of Plantar |url=https://www.merriam-webster.com/dictionary/plantar |website=www.merriam-webster.com |access-date=16 March 2025 |language=en}}</ref> 

Similarly, in the [[limb (anatomy)|limbs]] for clarity, the sides are named after the bones. In the [[forearm]], structures closer to the [[radius (bone)|radius]] are '''radial''', structures closer to the [[ulna]] are '''ulnar''', and structures relating to both bones are referred to as '''radioulnar''', such as the [[distal radioulnar joint]].<ref name="Dyan">{{cite journal|author=Dyan V. Flores |author2=Darwin Fernández Umpire |author3=Kawan S. Rakhra |author4=Zaid Jibri |author5=Gonzalo A. Serrano Belmar |journal= Radiographics|title=Distal Radioulnar Joint: Normal Anatomy, Imaging of Common Disorders, and Injury Classification|date=18 Nov 2022|volume=43 |issue= 1|pages= e220109|url=https://pubs.rsna.org/doi/10.1148/rg.220109|doi=10.1148/rg.220109|pmid=36399415 |s2cid=253627145 }}</ref> Similarly, in the [[Human leg|lower leg]], structures near the [[tibia]] (shinbone) are '''tibial''' and structures near the [[fibula]] are '''fibular''' (or '''peroneal''').

===Rotational direction===
{{multiple image
 | align = right
 | total_width = 425

 | image1 = Gray1230.png
 | image2 = Atlas and epitome of gynecology (1900) (14761581924).jpg
 | footer = Image showing an '''anteverted''' [[uterus]] lying above the [[urinary bladder|bladder]] (above), compared with a '''retroverted''' uterus undergoing [[bimanual examination]] facing towards the [[rectum]] (below)
}}

'''Anteversion''' and '''retroversion''' are complementary terms describing an anatomical structure that is rotated forwards (towards the front of the body) or backwards (towards the back of the body), relative to some other position. They are particularly used to describe the curvature of the [[uterus]].<ref name="Collins2025a">{{cite web |title=Anteversion definition and meaning {{!}} Collins English Dictionary |url=https://www.collinsdictionary.com/dictionary/english/anteversion |website=www.collinsdictionary.com |access-date=15 March 2025 |language=en}}</ref><ref name="Collins2025b">{{cite web |title=Retroversion definition and meaning {{!}} Collins English Dictionary |url=https://www.collinsdictionary.com/dictionary/english/retroversion#google_vignette |website=www.collinsdictionary.com |access-date=15 March 2025 |language=en}}</ref>
* '''Anteversion''' ({{ety|la|anteversus}}) describes an anatomical structure being tilted further ''forward'' than normal, whether pathologically or incidentally.<ref name="Collins2025a"/> For example, a woman's [[uterus]] typically is anteverted, tilted slightly ''forward''. A misaligned [[pelvis]] may be anteverted, that is to say tilted ''forward'' to some relevant degree.<ref name="Zhou2024">{{cite journal |last1=Zhou |first1=S |last2=Zhao |first2=Y |last3=Sun |first3=Z |last4=Han |first4=G |last5=Xu |first5=F |last6=Qiu |first6=W |last7=Liu |first7=T |last8=Li |first8=W |title=Impact of pelvic anteversion on spinopelvic alignment in an asymptomatic population: a dynamic perspective of standing and sitting. |journal=The Spine Journal |date=September 2024 |volume=24 |issue=9 |pages=1732–1739 |doi=10.1016/j.spinee.2024.04.001 |pmid=38614156}}</ref>
* '''Retroversion''' ({{ety|la|retroversus}}) describes an anatomical structure tilted ''back'' away from something.<ref name="Collins2025b"/> An example is a [[retroverted uterus]].<ref name="Collins2025b"/>

===Other directional terms===
Several other terms are also used to describe location. These terms are not used to form the fixed axes. Terms include:

* '''Axial''' ({{ety|la|axis|axle}}): around the central axis of the organism or the extremity.<ref>{{cite web |title=Definition of Axial |url=https://www.merriam-webster.com/dictionary/axial |website=www.merriam-webster.com |access-date=15 March 2025 |language=en |date=15 March 2025}}</ref> Two related terms, "abaxial" and "adaxial", refer to locations away from and toward the central axis of an organism, respectively<ref>{{cite web |title=Definition of Abaxial |url=https://www.merriam-webster.com/dictionary/abaxial |website=www.merriam-webster.com |access-date=15 March 2025 |language=en}}</ref>
* '''Luminal''' ({{ety|la|lumen|light, opening}}): on the—hollow—inside of an organ's [[Lumen (anatomy)|lumen]] (body cavity or tubular structure);<ref>{{cite web|url=https://www.medicinenet.com/lumen/definition.htm |title=Medical Definition of Lumen |author=William C. Shiel |publisher=MedicieNet |access-date=12 December 2020}}</ref><ref>{{cite web|url=https://www.cancer.gov/publications/dictionaries/cancer-terms/def/lumen |title=NCI Dictionary of Cancer Terms "lumen" |publisher=[[National Cancer Institute]] |access-date=12 December 2020}}</ref> '''adluminal''' is towards, '''abluminal''' is away from the lumen.<ref>{{cite web|url=https://www.merriam-webster.com/medical/abluminal |work=[[Merriam-Webster]].com Medical Dictionary |title="abluminal"|access-date=12 December 2020}}</ref> Opposite to '''outermost''' (the [[adventitia]], [[serosa]], or the cavity's wall).<ref>{{cite web|url=http://www.siumed.edu/~dking2/erg/giguide.htm |title=Study Guide - Histology of the Gastrointestinal System |publisher=Southern Illinois University |author=David King |year=2009 |access-date=12 December 2020}}</ref>
* '''Terminal''' ({{ety|la|terminus|boundary or end}}) at the extremity of a usually projecting structure; forming the end of a structure such as an [[axon terminal]].<ref>{{cite web |title=Definition of Terminal |url=https://www.merriam-webster.com/dictionary/terminal |website=www.merriam-webster.com |language=en |date=15 March 2025}}</ref>
* '''Visceral''' ({{ety|la|viscera|internal organs}}): associated with the innermost layer of an [[Organ (biology)|organ]] within the body. For example, the [[visceral pleura]] covering the [[lung]]s, contrasted with the [[parietal pleura]] lining the thoracic cavity.<ref name="radiopedia">{{cite web |title=Pleura |url=https://radiopaedia.org/articles/pleura?lang=gb |access-date=10 March 2025}}</ref>
* '''Parietal''' ({{ety|la|paries|wall}}): pertaining to the wall of a body cavity as the parietal pleura lining the thoracic cavity, contrasted with visceral pleura.<ref name="radiopedia"/>
* '''Aboral''' (away from '''oral''') is used to denote a location in an organism that is further from the mouth.

==Other animals and organisms==
Different terms are used because of different [[body plan]]s in animals, whether animals stand on two or four legs, and whether an animal is symmetrical or asymmetrical. For example, as humans are [[symmetry in biology|bilaterally symmetrical]], anatomical descriptions usually use the same terms as those for other vertebrates.<ref name="Hyman"/> However, the standard human anatomical position means that their anterior/posterior and ventral/dorsal directions are the same, so the inferior/superior directions are used due to longstanding tradition instead of cranial/caudal, which apply regardless of position, as in other species.<ref name= "Latin Tucker">{{cite book | author= Tucker, T. G.| title = A Concise Etymological Dictionary of Latin | publisher = Max Niemeyer Verlag | location = Halle (Saale)| year = 1931 }}</ref> The term "rostral" used to refer to the beak or nose in some animals is used less frequently in humans, with the exception of parts of the brain;<ref name="Purves1"/> while humans do not have a visible tail (the [[coccygeal vertebrae]] are present and commonly called the "tailbone") the term "caudal" that refers to the tail-end is also sometimes used in humans and animals without tails to refer to the hind part of the body.<ref name="Purves1"/> [[Flounder]] and other flatfish which lie on the seabed on their left or right side are asymmetric, with both eyes on the 'up' side, making anatomical nomenclature a challenge.<ref>{{cite web |title=Flatfish such as Flounder and Sole |url=https://ioa.factsanddetails.com/article/entry-217.html |website=Sealife, Islands and Oceania: Facts and Details |access-date=12 March 2025}}</ref>

[[Invertebrates]] have a large variety of body shapes that can present a problem when trying to apply standard directional terms. Depending on the organism, some terms are taken by analogy from vertebrate anatomy, and appropriate novel terms are applied as needed. Some such borrowed terms are widely applicable in most invertebrates; for example proximal, meaning "near" refers to the part of an appendage nearest to where it joins the body, and distal, meaning "standing away from" is used for the part furthest from the point of attachment. In all cases, the usage of terms is dependent on the body plan of the organism.

<gallery>
Direcoes anatomicas.svg|Anatomical terms of location in a [[dog]]
Anatomical-directions-kangaroo.svg|Anatomical terms of location in a [[kangaroo]]
Anatomical Directions and Axes.JPG|Anatomical terms of location in most [[fish]]
Horse Axes.JPG|Anatomical terms of location in a [[horse]]
File:Pseudopleuronectes americanus.jpg|[[Flatfish]] are asymmetric, with both eyes lying on the same side of the head. 

</gallery>

===Non-bilaterian organisms===
[[Image:Asymmetrical and Spherical.JPG|thumb|right|250px|Asymmetrical and spherical [[body plan|body shapes]]. (a) An organism with an asymmetrical, amoeboid body plan (''Amoeba proteus''{{snd}} an amoeba). (b) An organism with a spherical amoeboid body plan (''Actinophrys sol''{{snd}} a [[heliozoan]]).]]

In [[non-bilaterian]] organisms with a changeable shape, such as [[amoeboid]] organisms, most directional terms are meaningless, since the shape of the organism is not constant and no distinct axes are fixed. Similarly, in [[radially symmetrical]] organisms, there is nothing to distinguish one line through the centre of the organism from any other. An indefinite number of triads of mutually perpendicular axes could be defined, but any such choice of axes would be useless, as nothing would distinguish a chosen triad from any others. In such organisms, only terms such as ''superficial'' and ''deep'', or sometimes ''proximal'' and ''distal'', are usefully descriptive.

===Elongated organisms===
[[Image:Longitudinal Diatom (Labelled).JPG|thumb|right|Four individuals of ''[[Phaeodactylum tricornutum]]'', a [[diatom]] with a fixed elongated shape]]
In organisms that maintain a constant shape and have one dimension longer than the other, at least two directional terms can be used. The ''long'' or ''longitudinal axis'' is defined by points at the opposite ends of the organism. Similarly, a perpendicular ''transverse axis'' can be defined by points on opposite sides of the organism. There is typically no basis for the definition of a third axis. Usually such organisms are [[planktonic]] (free-swimming) [[protists]], and are nearly always viewed on [[microscope slide]]s, where they appear essentially two-dimensional. In some cases a third axis can be defined, particularly where a non-terminal [[cytostome]] or other unique structure is present.<ref name="Ruppert2004">{{cite book |last1=Ruppert |first1=EE |last2=Fox |first2=RS |last3=Barnes |first3=RD |title=Invertebrate zoology: a functional evolutionary approach |date=2004 |publisher=Thomson-Brooks/Cole |location=Thomson, Belmont |isbn=0-03-025982-7 |edition=7th}}</ref>

<!-- Apical (anatomy) and Basal (anatomy) redirect here -->
[[Image:Labelled Ciliates.JPG|thumb|Organisms where the ends of the long axis are distinct (''[[Paramecium caudatum]]'', above, and ''[[Stentor roeselii]]'', below).]]<!-- Do we need both of these images? They are creating a big blank spot on the page. -->
Some elongated [[protists]] have distinctive ends of the body. In such organisms, the end with a mouth (or equivalent structure, such as the [[cytostome]] in ''[[Paramecium]]'' or ''[[Stentor (ciliate)|Stentor]]''), or the end that usually points in the direction of the organism's [[Animal locomotion|locomotion]] (such as the end with the [[flagellum]] in ''[[Euglena]]''), is normally designated as the '''anterior''' end. The opposite end then becomes the '''posterior end'''.<ref name="Ruppert2004" /> Properly, this terminology would apply only to an organism that is always [[planktonic]] (not normally attached to a surface), although the term can also be applied to one that is [[Sessility (zoology)|sessile]] (normally attached to a surface).<ref>{{cite book |title=On the Origin of Phyla |last=Valentine |first=James W. |year=2004 |publisher=University of Chicago Press |location=Chicago |isbn=978-0-226-84548-7 }}</ref>

{{Anchor|apical}}
[[Image:Venus Flower Basket (sponge-labelled).JPG|thumb|right|A cluster of [[Venus' Flower Basket|''Euplectella aspergillum'' sponges (Venus flower baskets)]], showing the apical–basal axes]]

Organisms that are attached to a [[Substrate (biology)|substrate]], such as [[Porifera|sponges]] and [[Protista|animal-like protists]] also have distinctive ends. The part of the organism attached to the substrate is usually referred to as the '''basal end''' ({{ety|la|basis|support/foundation}}), whereas the end furthest from the attachment is referred to as the '''apical end''' ({{ety|la|apex|peak/tip}}).

===Radially symmetrical organisms===
[[Radial symmetry|Radially symmetrical organisms]] include those in the group [[Radiata]]{{snd}} primarily [[Cnidaria]]ns ([[jellyfish]], [[sea anemones]] and [[corals]], and the [[Ctenophora|comb jellies]]).<ref name="Ruppert2004B">{{cite book |last1=Ruppert |first1=EE |last2=Fox |first2=RS |last3=Barnes |first3=RD |title=Invertebrate zoology: a functional evolutionary approach |date=2004 |page=112|publisher=Thomson-Brooks/Cole |location=Thomson, Belmont |isbn=0-03-025982-7 |edition=7th}}</ref> Adult [[Echinodermata|echinoderms]], such as [[starfish]], [[sea urchin]]s, [[sea cucumber]]s and others are also included, since they have a [[Radial symmetry|pentamerous symmetry]] having five [[rotational symmetry#n-fold rotational symmetry|discrete symmetric parts]] arranged around a central axis.<ref name="Ruppert2004A">{{cite book |last1=Ruppert |first1=EE |last2=Fox |first2=RS |last3=Barnes |first3=RD |title=Invertebrate zoology: a functional evolutionary approach |date=2004 |pages=873–875|publisher=Thomson-Brooks/Cole |location=Thomson, Belmont |isbn=0-03-025982-7 |edition=7th}}</ref> Echinoderm [[larva]]e are not included, since they are [[symmetry in biology|bilaterally symmetrical]].<ref name="Ruppert2004A"/> 

Cnidarians  have an incomplete digestive system, meaning that one end of the organism has a mouth, the '''oral end''' ({{ety|la|ōrālis|of the mouth}}), and the opposite '''aboral end''' ({{ety|la|ab-|away from}}) has no opening from the gut (coelenteron).<ref name="Ruppert2004B"/> They are radially symmetric around the '''oral-aboral axis'''.<ref name="Ruppert2004B"/> Having only the single distinctive axis, "lateral", "dorsal", and "ventral" have no meaning, and all can be replaced by the generic term '''peripheral''' ({{ety|grc|περιφέρεια|circumference}}). '''Medial''' can be used, but in the case of radiates indicates the central point, rather than a central axis as in vertebrates. Thus, there are multiple possible '''radial axes''' and '''medio-peripheral''' (half-) '''axes'''.<ref name="Oliveira2007">{{cite web |last1=Oliveira |first1=Otto Müller Patrão de |title=Chave de identificação dos Ctenophora da costa brasileira |url=https://www.researchgate.net/figure/Symmetry-planes-of-the-ctenophores-using-Bolinopsis-vitrea-as-model-a-view-of-the_fig1_247853778 |publisher=Biota Neotropica |access-date=6 April 2023 |ref=Oliveira2007}}</ref>

Comb jellies have a biradial symmetry about only two planes, a tentacular plane, and a pharyngeal plane.<ref name="Ruppert2004C">{{cite book |last1=Ruppert |first1=EE |last2=Fox |first2=RS |last3=Barnes |first3=RD |title=Invertebrate zoology: a functional evolutionary approach |date=2004 |page=184|publisher=Thomson-Brooks/Cole |location=Thomson, Belmont |isbn=0-03-025982-7 |edition=7th}}</ref>

<gallery widths="220" heights="110">
Image:Radiate Radial Axes.JPG|''[[Aurelia aurita]]'', another species of [[jellyfish]], showing multiple radial and medio-peripheral axes
File:Porania_pulvillus.jpg|The [[sea star]] ''[[Porania pulvillus]]'', aboral and oral surfaces
</gallery>
{{clear}}

===Spiders===
{{See also|Glossary of spider terms|Spider anatomy}}

Special terms are used for [[spiders]]. Two such terms are useful in describing views of the legs and [[pedipalp]]s of spiders, and other [[arachnid]]s. '''Prolateral''' refers to the surface of a leg that is closest to the anterior end of an arachnid's body. '''Retrolateral''' refers to the surface of a leg that is closest to the posterior end of an arachnid's body.<ref name="Kaston1972">{{cite book|last=Kaston|first=B.J.|author-link=B. J. Kaston|title=How to Know the Spiders|edition=3rd|year=1972|page=19|publisher=W.C. Brown Co.|location=Dubuque, IA|isbn=978-0-697-04899-8 |oclc=668250654 }}</ref> Most spiders have eight eyes in four pairs. All the eyes are on the [[carapace]] of the [[prosoma]], and their sizes, shapes and locations are characteristic of various spider families and other [[taxon|taxa]].<ref name=FOELIX2011>{{cite book|last1=Foelix|first1=Rainer|title=Biology of Spiders|date=2011|publisher=Oxford University Press, US|isbn=978-0-19-973482-5|pages=17–19|url=https://books.google.com/books?id=eOUVDAAAQBAJ&q=arachnid+anatomy|ref=Foelix2011|language=en}}</ref> Usually, the eyes are arranged in two roughly parallel, horizontal and symmetrical rows of eyes.{{r|FOELIX2011}} Eyes are labelled according to their position as anterior and posterior lateral eyes (ALE) and (PLE); and anterior and posterior median eyes (AME) and (PME).{{r|FOELIX2011}}

<gallery>
File:Palystes superciliosus male anterior 2012 03 04 3452.JPG|Aspects of spider anatomy. This aspect shows the mainly prolateral surface of the anterior femora, plus the typical horizontal eye pattern of the [[Sparassidae]].
File:Hogna species female Lycosidae showing eye pattern EOS 027s.jpg|Typical arrangement of eyes in the [[Lycosidae]], with PME being the largest
File:Salticidae Male Anterior annotated.jpg|In the [[Salticidae]] the AME are the largest.
</gallery>

==See also==
* [[Chirality]]
* [[Geometric terms of location]]
* [[Reflection symmetry]]

==References==
{{Reflist|2}}


{{anatomy}}
{{Authority control}}

{{DEFAULTSORT:Anatomical Terms Of Location}}
[[Category:Anatomy| ]]
[[Category:Animal anatomy]]
[[Category:Medical terminology]]
[[Category:Orientation (geometry)]]
[[Category:Position]]